Abstract: There are 8 strong edge-bottom water common heavy oil reservoirs in Hekou oil production plant of Shengli oilfield.At present,it is at high water cut period,but the recovery degree is low and the remaining oil is abundant.Due to active edge-bottom water,it can't meet the screening standard of steam drive.Based on the characteristics of block development,with the numerical simulation method,the economic and technical limit of well pattern infilling at high water cut stage has been analyzed,and the index, " encryption",has been put forward to make a judgment on whether the well pattern infilling is economic and feasible.Research results indicate when there is no inter-layer,the well pattern at present can not effectively produce the crude oil between wells.When the effective thickness is of 6.7 ~ 8.7m,steam stimulation can be adopted for well pattern infilling.When there is the inter-layer,the interwell oil has been produced,and there is no economic benefits for well pattern infilling.